This invention relates to magnesium chloride. More particularly it relates to magnesium chloride employed as a support material for the titanium-containing component in a coordination complex (Ziegler-Natta) catalytic system for the polymerization of olefins. Magnesium chloride is a favored support material for such polymerization catalysts, as disclosed, for example in U.S. Pat. No. 3,642,746 granted to Kashiwa et al.
Magnesium alkyls are useful reagents in organic reductions, metalation of aromatic compounds, alkylating agents, and catalysts. As disclosed in U.S. Pat. No. 4,127,507 granted to Fannin and Malpass magnesium alkyls may be prepared by the reaction of alkyl chlorides with magnesium metal, but in this process impure magnesium chloride is formed as an inevitable by-product. Hitherto there has been no effective means for transforming the waste, by-product magnesium chloride generated by the production of magnesium alkyls into a grade of magnesium chloride generally useful in industry as a support material suitable for the catalyst for the polymerization of olefins. Magnesium chloride is also useful in the preparation of oxychloride cements, as a fireproofing agent for wood timbers, as a dustbinder cleaning component, and in refrigeration brines.
U.S. Pat. No. 4,180,636 to Hirota et al. discloses a process for preparing a catalytic component for polymerizing olefins by copulverizing magnesium dihalide, aroyl chloride, titanium halide, and an electron donor. Among the recommended electron donors are phosphinites, phosphites, chlorophosphites, phosphinates, phosphonates, phosphates, and phosphine oxides. Other electron donors include phenols and naphthols.
U.S. Pat. No. 4,243,552 to Welch et al. discloses copulverization of a magnesium or manganese halide with selected adjuvants followed by treatment with a tetravalent titanium halide. Among the adjuvants listed are organophosphites, organophosphates, and phenols.
Japanese Pat. No. 2,032,985 to Nippon Oil KK discloses a component for an olefin polymerization catalyst prepared by copulverizing magnesium chloride, a hydrocarbyl phosphite, titanium tetrachloride, and titanium trichloride.
U.S.S.R. Pat. No. 667,232 to Makhtarulin discloses a catalyst for polymerizing ethylene obtained by post-treating with titanium tetrachloride a complex magnesium alkyl and magnesium chloride prepared from magnesium metal and an alkyl chloride.
It is an object of this invention to yield a catalyst support for use in the polymerization of an olefin in such a manner that a high weight of polymer is produced for each gram of catalyst, so that a deashing step can be omitted. It is a further object of this invention to provide a polymerization catalyst for olefins which gives a high isotactic index for the polymer produced.
Additionally, it is an object of this invention to provide an effective catalyst support of magnesium dichloride from an impure magnesium dichloride by-product, originally containing an unacceptable amount of elemental magnesium.
Still another object of the present invention is to provide a process for preparing magnesium chloride of polymerization catalysis grade from a by-product material from the manufacture of magnesium alkyls.
An additional object of this invention is to provide a process for making commercially useful magnesium chloride from an impure by-product of little value.
Other objects of the present invention will be apparent to those skilled in the art.